Many types of flotation devices exist with differing characteristics.
Damper plates and toroid shaped flotation devices have been used to create buoys in the form of so-called “wave follower” buoys. For example, see Buoy Engineering, H. O. Berteaux, John and Sons, 1976 Pg. 212-213. Wave follower buoys are subject to relatively small amounts of motion relative to the motion of the ocean surface that they follow. However, in the presence of waves, the wave follower buoy experiences a relatively large amount of absolute heave and pitch due to the heave and pitch of the wave surfaces.
A so called “spar buoy” has less absolute heave and pitch as it tends to have a smaller cross section at the water level than a wave follower buoy, but unless the spar buoy has substantial length it will submerge in larger waves. Mass of the spar buoy can also be distributed to create a righting moment. This will decrease absolute pitch. However, spar buoys tend to experience large amounts of rotation about a central vertical axis, vertically oriented relative to the surface of the water.
An object suspended beneath a spar buoy in the presence of waves has a tendency to increase the absolute pitch, roll, and heave of the spar buoy.
It would be desirable to provide a buoy having reduced amounts of rotation about a central vertical axis than a spar buoy in some applications.